The downing of Malaysia Airlines flight MH17 threatens to escalate a tense, months-long stand-off between the west and Russia over Ukraine to dangerous new levels.
As Moscow and Kiev traded accusations about who was responsible, the US pointed the finger squarely at Russian-backed separatists in east Ukraine for firing the missile that destroyed the plane.
The incident is galvanizing opinion in the EU, which has so far lagged behind the US in its willingness to impose tough economic sanctions on Russia. In the wake of the disaster, more hawkish European capitals launched a fresh push for quicker and broader new measures.
Asked about possible further sanctions, US President Barack Obama said on Friday the crash was "a wake-up call for Europe and the world that there are consequences to an escalating conflict in eastern Ukraine".
Moscow could end up facing more concerted western pressure to end its support for the eastern rebels. In the meantime, the disaster has changed – if temporarily – one of the prevailing dynamics of the Ukraine crisis: a Russian leader who has until now called most of the shots and succeeded at dividing western governments with ease suddenly appeared on the back foot.
"The context for yesterday's horror is clear: separatist forces – backed by the Russian government – continue to destabilize Ukraine and undermine the efforts of Ukraine's elected leaders to build a democratic Ukraine," Samantha Power, US ambassador to the UN, told an emergency session of the Security Council. "If President Putin continues to choose escalation over de-escalation, the international community will continue to impose costs on Russia."